Video monitoring systems are commonly used to monitor various commercial or retail locations such as stores, warehouses, athletic facilities, and the like. In general, video monitoring systems are used to monitor various interior locations (e.g., high-traffic aisles, security sensitive areas, etc.) and exterior locations (e.g., parking lots, loading docks, external doors, etc.) of such facilities.
The purposes for video monitoring vary, depending on the type of facility or the facility location. For example, video monitoring in a jewelry store is used primarily for store security, and may help to prevent theft or to identify perpetrators and recover merchandise after a theft has occurred. As another example, video monitoring in an athletic facility is used primarily for safety purposes or to monitor for overflow capacity of a particular area.
Regardless of the purpose, trained personnel can monitor video in real-time in order to react to ongoing incidents, or can monitor and review recorded video to study previous incidents. For example, stored video may be used for training purposes, such as demonstrating an accident or shoplifting prevention techniques. As another example, a theft captured on video may be used as evidence by law enforcement. Videos are generally stored on magnetic tapes, optical discs, hard drives, or flash-based storage, to name a few examples, in an analog or digital format.
Due to the large volume of data associated with a typical video recording, videos are often compressed. A variety of compression methods (e.g., MPEG-1, MPEG-2, etc) and standards (e.g., lossy or lossless) may be selected, based on media limitations and associated storage limitations. For example, spatial compression, temporal compression, and motion compensation are different methods often used in conjunction to reduce file size. Many video compression methods depend on limits to human perception, such as discrete cosine transformations and chroma subsampling.